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CBD Rail Tunnel – the 2004 study

By Joshua Arbury, on October 27th, 2009

The CBD Rail Tunnel project has been proposed for around 80 years now, and has popped up at various point during that time: in the 1920s, the 1950s, the 1970s and most recently since 2004. This latest occasion will hopefully be the “real thing”, and we will finally get this critical project constructed after 80 years. Given that the current study into this project will clearly build upon previous work, I think it’s a good idea to have a look at what we already do know about possible alignments, grade issues and station locations. Which is why it was pretty handy to get my hands on the full copy of the 2004 URS Report into the CBD Rail Tunnel this week (warning, it’s about a 10mb PDF file!)

There are a number of interesting aspects to this report, most notably the different options that were looked at regarding preferred alignments, the different possible station locations, the consequences of different grades for the tunnel, and perhaps most interestingly – a relatively detailed look into both the business case for the project and a look at how much it might cost.

Firstly, if we have a look at the different alignments that were considered we can see a whole range of options were looked at, but eventually it became fairly obvious that the route that was eventually chosen was the obvious preferred option. The map below shows the different alignments that were considered: These different options are described below:

Option 1: Albert Street ridge line/Pitt Street/Mercury Lane/under the Southern Motorway/Upper Queen Street/Newton Rd under New North Road to the Western Rail Line;

Option 2A: As per Option 1, except for improving the operation of the alignment by removing curvesnear Karangahape Road and Upper Queen Street. The gradient is 3.0%;

Option 2B: As per Option 1, except for improving the operation of the alignment by removing curvesnear Karangahape Road and Upper Queen Street. The gradient is 3.5%;

When the different options were analysed, option 1 was discarded because its alignment resulted in too many sharp horizontal curves which slowed down services and reduced efficiency; options 2A and 2B were carried forward as the preferred alignment (I think 2A is better so that the tunnel’s grade is minimised); options 3A and 3B were discarded as it was found to not be technically feasible to operate trains along the grades necessary to clear the messy New North Road/Ian McKinnon drive interchange; option 4 was discarded once again because its grade was too steep (and it would also get very close to the underground Aotea carpark) while option 5 was considered not feasible because its stations would be a long long way underground plus the extra length of the route would add significant cost to the project.

I agree with the conclusions made in this report, that option 2 (preferably 2A) is the best alignment. I had wondered about something along the lines of options 3A and 3B, as that seems to mirror the original alignment of the ‘Morningside Deviation’, as this project used to be known. However, I can see how the location of the New North Road/Ian McKinnon Drive interchange would make that option difficult if not impossible.

As I have explained previously, the gradient of the tunnel does still push the limits of what is feasible (a large part of the reason why I support option 2A rather than 2B). The image below shows a cross-section of the two options – with the green line showing the alignment of the tunnel and the red line showing a cross-section of ground level. Of most interest is to see (it’s a bit small on the image below sorry so you’ll have to download the PDF or trust me on it) that at the K Road station the track is about 28-31m below ground level, that the tunnel will pass about 20m below state highway one just to the south of K Road, that that Mt Eden station itself will be about 20m below ground level and that the Midtown station will also be about 18m below Albert Street.

The alignment of the tracks at both portals is also quite interesting. At Britomart the tunnel will link into the current system through an extension of the tracks that serve platforms 1 and 5. These will continue underneath QEII square (what’s left of it) and the downtown shopping centre before turning a sharp left and heading underneath Albert Street. There has been some thought into how this could integrate with a future North Shore Rail Link, although to “grade separate” those two lines (which is probably necessary) there would be significant extra cost. The aerial photo below shows the possible alignment of the tracks around this northern end of the tunnel: At the Mt Eden end of the tunnel the difference between options 2A and 2B becomes more obvious. As 2A has a lower grade within the tunnel, it will emerge much lower than option 2B. Therefore its tunnel/trench is far longer, and the western line also needs to be lowered throughout this area into a tunnel. This is further detailed in the diagram below: Looking at the above image, I actually think that option 2A would be preferable in another sense, and that is ensuring that we don’t end up with a giant wasteland created by the rail triangle that the yellow portal area (option 2B) would create. This whole area will need to be acquired for the construction of the link, but if it can be capped and then redeveloped there is the opportunity to really revitalise this part of the city – and for KiwiRail/Ontrack to hopefully make back quite a bit of money through redeveloping it.

I talked about the preferred station locations in detail in my previous post on this project, and these are basically identical to what has been proposed in the URS report, which I include below: Now of course, the big questions come down to “what will it cost” and “it is justified”? This is where things get a bit messy in the URS report, as it proposes a cost of around $500 million for this project – whereas subsequent analyses have put a more likely cost at around $1.5 billion: three times as much. Now I have wondered “how could they have under-estimated so much?”, although having a look through the analysis that was done to work out the costs it seems as though URS were fairly robust in their work. The breakdown of this cost is outlined below:

I must say that a $1 billion or more construction cost does sound more realistic to me than this amount.

In terms of “is it worth it?”, obviously at some stage a full cost-benefit analysis of the project will need to be undertaken, and the URS report really only makes a tentative beginning at that. I have always considered that the biggest benefits of the CBD Rail Tunnel might be quite difficult to measure, with things like effects on development within the CBD, the fact that it makes possible other extensions to the rail network, and the mess that will happen at Britomart if this does not happen, all being potentially difficult matters to properly “measure” when working out a full cost-benefit analysis. The URS report highlights these difficulties:

This is a complex project due to uncertainty as to how the network will change and evolve and the timing of those changes particularly if the tunnel is constructed – patronage and train operating pattern are unclear at this stage. For instance, if the tunnel and stations are completed before the need or decision to electrify and double track Mt Eden to Newmarket, and to enhance the station and the approach to Newmarket Station then considerable savings can be made. If the tunnel is completed after these investments then they are sunk costs and no savings can be made.

The most significant benefit is the opportunity for Auckland City to re-establish the CBD as a place for work, entertainment, recreation, health services and education. It is almost impossible to value this aspect. Patronage is difficult to forecast. Currently, only 12% of the Region’s work force works in the CBD. Only 35% of the people coming over the harbour bridge go to the CBD, the rest go elsewhere. More people cycled to work in the CBD than used the train in 2001.

Readers should note that this is an economic not a financial analysis – some of the benefits are intangible: such as the benefits of less pollution and increased reliability of travel time. Other benefits do not result in any cash accruing to the rail system operator.

Even with this extremely conservative approach to measuring the project’s potential benefits, URS estimated that the project would be economically viable in 2009 if some of those additional benefits were taken into account – and by 2019 it would very much be economically viable. An upgrade to Britomart by 2009 was anticipated when the report was written (that has been fairly accurate as we are now upgrading Britomart to handle an extra six trains an hour through bi-directional running) and then again by 2021 (the full tunnel construction) due to rising patronage.

Of course, this analysis was based on a $500 million construction cost, and if the cost is now $1.5 billion then the project will need to have three times its previous benefits to still be economically viable. However, I very much do think that this is possible because a huge number of benefits were ignored by the previous analysis. For example, in ARTA’s Auckland Transport Plan it was mentioned that the CBD Rail Tunnel could provide $2.4 billion in benefits through “releasing the economic potential” of the CBD and other inner suburbs on the railway system.

All in all, I think it’s interesting to get the full picture of what work has been conducted previously on this critical project. It will be interesting to see what the current study concludes with regards to alignments, station locations, costs and – most importantly really – the final economic analysis of the proposal. I do hope that a wider economic analysis is undertaken, so that the significant wider benefits of the CBD Rail Tunnel are included.

21 comments to CBD Rail Tunnel – the 2004 study

I think this is all still basically the way to go, I just hope in the current study they can extend their scope a little further. If anything this proposal is a touch unambitious.

I would suggest a two track tunnel on the same alignment and with the same stations, except with:
– Allowance for signalling and train control to allow for 90sec headways in the future
– Stations with separate access and egress platforms (spanish solution style, including possibly recovering the ‘light rail’ space at Britomart for this purpose) and plenty of pedestrian capacity.
– Grade separation of Mt Eden interchange, as ideally trains would head in both directions in equal numbers exiting the portal
– Allowing for at least a grade separated future North Shore line (but preferably a separate twin track tunnel entirely)

These additions would not add that much to the capital expenditure, but would allow the tunnel to operate perhaps twice as many trains at maximum.

Also, I think that the first stage of this project should be (at the least) to quadruplicate the eastern approach to Britomart, and more importantly to provide extra terminal capacity in the short term and to allow terminating trains to access Britomart without interfering with tunnel bound services in once the tunnel is built.

Even better than this would be if the tunnel itself was started at a grade separated junction at Quay Park with new tunnel platforms alongside Britomart, connected to the same concourse. This would allow tunnel-bound services to operate at the full capacity of the rest of the tunnel, while the existing Britomart terminal station could keep using it’s own approach tunnel for terminating diesel and electric services.

I think they should just leave Britomart as it is, maybe saving the links to platforms 1 and 5 for the future north shore line, and build a purpose built metro tunnel alongside. It might even work out cheaper if it allowed a less constrained alignment, provided easier construction staging and avoided all the difficult works required to pass under the old CPO building and reach the existing platforms.

I agree with Nick’s comments about future proofing, it won’t happen however as it will cost at least one dollar extra now and thats just not the Auckland way, we’d rather pay a hundred dollars later thanks…

It looks like the guys doing the current study have something pretty comprehensive to base their study on, in fact what are they studying..? The old study methinks…

Be careful what you wish for on wider economic benefits though. The “$2.4 billion in benefits through “releasing the economic potential” of the CBD and other inner suburbs on the railway system” can be applied to plenty of roads too, which ends up being circular. The big issue is whether such benefits are a transfer of economic activity from elsewhere in the country, or new activity. I’ve examined wider economic benefit appraisals as they are often found wanting. Growth may have happened anyway, it may have happened elsewhere, it may be gains held primarily by property owners nearby (which means you need a serious contribution from those owners to make it worthwhile, like Crossrail is getting in London), or it may not happen at all. London’s Jubilee Line Extension cost a fortune, but undoubtedly unlocked Canary Wharf and allowed enormous growth in the financial sector that has benefited London, notwithstanding the current recession. Will a CBD rail tunnel unlock Auckland compared to Sydney or other major cities? THAT is the question. Transfers from elsewhere in the country are a negative because the rest of the country does not have such constrained transport networks or high land prices.

Honestly, I don’t know the answer, primarily because with such a small remote country, the odds that there is development and investment looking to go somewhere and Auckland’s lack of an underground rail loop hinders this, seems a bit low to me. Once electrification is completed and the Western Ring Route, I doubt it will make enough of a difference.

NZTA’s economic appraisal BCR excludes wider economic benefits except as a qualitative statement that might improve ranking compared to other options for the same problem, or give reason for rounding up the BCR by one tenth. Like all big transport projects that generate no revenue, the economic benefits have to more than offset the long run cost of capital to make them worthwhile.

Well if the question is “what transport-land use strategy will best unlock our potential to attract international capital” then we need to look at what our competitors have that we don’t.

One obvious thing is the fact that Auckland lacks anything more than a basic rapid transit network, while the other major Australasian centres have relatively advanced systems. A rail tunnel might not be the best way to go about achieving that, but considering the sunk investment that already exists in the rail network and it’s massive potential capacity expansion it seems like about the best option to me.

In the current globalised marketplace and ‘knowledge economy’ attracting and keeping talent is more important than providing the means to acquire resources, manufacture and distribute goods. When that becomes the key factor of economic growth, things like quality of life, access to services and entertainment and the like become very important, and easy access to places like the CBD and regional centres become paramount.

I like the idea of a triangular station at the Mt Eden end. It would certainly use far less land than having two stations. it would fit nicely within the triangle of lines and an opportunity to make it an iconic station – it certainly will be used by a lot of passengers who need to change lines. The Exmouth St station version is a bad idea: half the station entrances would be in Basque Park.

Another staging the CBD rail tunnel idea would be to initially built it to one track, with the Western line only using it as a loop (i.e. into Mt Eden, out at Britomart, then through newmarket and back out) as a one way system.

It could be widened to two tracks latter. It will mean only the western line gets the benefits, but could be built for maybe 60% the cost, and be built much sooner. It will also free some capacity at Britomart as Western line trains will only have to go out, not in.

I’m pretty sure there would be very little savings in building it as one track, the marginal cost of boring the extra tube of the main tunnel would be very minimal compared to the cost of all the other components. From the costing above you would save only around 1/6 of the total cost (that is by removing half the cost of the bored tunnel line item).

But when you went to add the second tube you would need to do all the road closures again, re-hire the gear and contractors, re-open the access pits at either end (that might not be possible once the existing tube is in use)and basically do the whole project over again. You would end up spending a lot more than just the cost of the extra tube.

Plus looping lines one way around the whole central area would be a serious mistake, two tracks or not.

Can we please all give up on the idea that the tunnel will be a city loop. City loops don’t work very well in the cities that have them, and the one in Auckland would be a good 50% longer than either Sydney’s or Melbourne’s (almost 10km long with seven stations on it, pretty crap to have to sit through all that if you want to go from Mt Eden to Kinglsand!).

If the full $1 – 1.5 billion is unaffordable is the short term, maybe it is possible to build the tunnel in stages. I was thinking maybe the Britomart to Wellesley Street section can be built first. If this section was able to be completed much quicker than the whole tunnel it would relieve the capacity constraints at Britomart that are expected from 2016. I would anticipate this staging of the project would allow Britomart to become a through station for at least some trains – I would expect Southern Line trains would run through to Wellesley and Western Trains would continue to terminate at Britomart. I would not expect this would add much extra cost to the proposal, although maybe the mechanics of the tunnel boring machines may make the idea pointless.
This would not be my preferred solution but if it enabled a quicker start date to the project it may have some advantages.

I certainly agree that staging project would be a seriously inferior solution however I am unfortunately rather pessimistic about this urgent project being able to proceed anytime soon, due to funding constraints and very unfriendly government policy. Whatever the transport priorities of the Mayor of Auckland are, they will not have access to anywhere near the amount of money that this project will need to proceed, as the Crown through Mr English and Joyce will still control the purse strings. I also dont want the project stuck being a PPP, as this would mean $100’s of millions of dollars being sent to Infratil (ahhh) or some even nastier overseas investment bank.

As an aside does the report indicate how long construction is expected to take, or if boring will take place from one end, and which end that might be?

I think there are only two sections that could work as a stand alone project (the CBD tunnel itself, and building a second tunnel between Quay Park and Britomart). That would be the only opportunity to stage the improvements, but that still means building the whole CBD tunnel (as described above) in one go.

Yes, it was the old ASB headquarters building on the corner of Queen and Wellesley Streets; it was designed and constructed c. 1970-71 (the ASB had previously been headquartered in what is now Macdonalds in Queen Street). I understand a set of stairs were built in at the western end of the basement with the intention that they would provide access to the northern end of the proposed Civic station.

Do you have any idea how the current study is progressing. It would be interesting to see their route designation to see if it differs much from the 2004 study. Also after looking at the costs of Waterview at $1.4 bil this would surely cost less. While it is longer by between half and 1 km it doesn’t need to be anywhere near as wide at about 2 lanes compared to 6 which means there is a lot less rock to excavate which much reduce time to build and therefore the cost. It also doesn’t need the ventilation that Waterview does but of course will need 3 deep stations. If the study costs this as less that $1 bil it should be hard to argue against it being built.